Italian foreign ministry has a page (http://www.esteri.it/visti/) available also in English for entry documents required to foreign nationals. Being Italy signatory to the Schengen treaty you don't have problems if you come with an Austrian or Swiss visa, being this two states member of Schengen too - although Switzerland is not a member of the European Union.
There are no border controls between Schengen Agreement nations - so also the last controls at the border to Switzerland have dissolved.
By bus
South Tyrol is very well connected by bus mainly with Germany and Eastern Central Europe. Traveling by bus is cheaper than by train and it could be a good solution if you find what you are looking for. The local travel agency Gross (http://www.gross.it) organizes up to 12 bus connections every month between Bolzano and Munich one-way ticket for EUR 25. Almost every important city in Poland is connected with Bolzano through international bus connections - normally arrival is in Genoa. The Polish travel agency Wikel (http://www.wikel.pl/wlochy.htm) is the most known for this cheap connections. If you are coming from Romania your reference could be the Romanian CentroTrans (http://www.cento.ro/) travel agency which has also offices in England. Coaches from Romania stops in Bolzano but also in Brixen. In the Romanian website about bus stations (http://www.autogari.ro/Au...) you can find arrivals and departures from Romania/to South Tyrol at the Bolzano bus station. Connections with Slovakia from/to Bratislava are operated by the Eurolines (http://www.slovaklines.sk...) agency in Bratislava. Connections with the Czech Republic are operated by the Tourbus (http://www.tourbus.cz/) agency web site also in English available with buses from Prague or Brno and other places. Prices are cheap - a return ticket from Brno to Bolzano costs EUR 94. Tourist connections are also available from Southern Germany, Austria and Switzerland - this connections are operated by the German travel agency Südtirol Tours (http://www.suedtiroltours.de/) or by the Swiss Südtirol Express (http://www.suedtirolexpress.ch). In winter bus transfers between low cost airports in Northern Italy and tourist destinations are available - for this check on the official tourism board web site.
By plane
The only airport in South Tyrol is the Airport Bolzano Dolomites located in the capital city Bolzano and flights are operated mainly by Air Alps (http://www.airalps.at) in code-sharing with Alitalia.
Nearest major hubs are in Munich, Germany and Milan while other airports near South Tyrol are located in Innsbruck, Austria and Verona. Low cost flights only to/from Verona, Treviso or Bergamo. Airport transfers are available. Normally Inghams offers direct flights from England in winter.
By car
South Tyrol is a forced route if you want to travel from Italy to Germany - so it's simply to get in by car. Through South Tyrol passes the motorway A22 (http://www.autobrennero.it) known also as the Brenner Motorway that split the region into two side - west and east. In Austria the Brenner motorway is coded as A13 and while identification road signs in Italy are green in Austria they are blue also in Germany. In South Tyrol there are 8 motorway exits two of them only in Bolzano while tool booths are only in 6 exits - in Sterzing you will pay for the remaining itinerary. For a car which goes from Neumarkt-Auer to Brenner you will pay EUR 5.40 and from Bolzano South and Bolzano North EUR 0.60 March 2007. On the web site of the A22 society you can check the fare you might have to pay. The motorway charges a fee except in case of strikes involving the staff at the booths. For driving on Austrian motorways you have to buy the Vignette available for a 10-days, 2-months and 1-year-validity - for a car a 10-days-validity vignette costs EUR 7.60 2007. An exception is on the route between Innsbruck South and Brenner - here you have to pay EUR 8.00 for the whole itinerary at the booths. German motorways are for free.
On the same side of the A22 motorway there is also the Statal Road 12 known also as Abetone-Brenner which is for free.If you come from East Tyrol nearest regions: Carinthia, Slovenia you will pass the border at Winnebach and the the route is for free, so it's also coming from Switzerland with the border at Taufers im Münstertal and from other mountain passes through South Tyrol like Reschenpass. You could have to pay a fee for passing the Jaufenpass on the Austrian side.