According to the MBS, item 13815 ("CENTRAL VEIN CATHETERISATION by percutaneous or open exposure") should be appropriate, though there are reports of mixed success when using this item number.
A PICC line inserted under anaesthesia should be billable under item 22020 (percutaneous central vein catheterisation under anaesthesia).
Both are valued as 5 RVG units for the first hour, then 1 RVG unit for each hour thereafter.
ASA item CV800 (use of ultrasound for major vascular access) may be appropriate if an ultrasound is used, but is not recognised by the MBS.
Alternatively some anaesthetists bill a PICC line as a 'referred anaesthetic consultation' , choosing the appropriate length item (eg. 17645).